Cross talk between melatonin and TGFβ1 in human benign prostate epithelial cells

BACKGROUND. Epithelial cells from the human benign prostate express melatonin receptors which effect transient suppression of DNA synthesis and sustained attenuation of growth. The role of transforming growth factor-β1 (TGFβ1), which is produced in prostate epithelial cells and inhibits their growth, was examined in the action of melatonin. METHODS. The effects of melatonin and TGFβ1 and their combination on ³H-thymidine incorporation were assessed. The possibility that melatonin effected TGFβ1 release from cells was studied. RESULTS. Incubation of the cells with TGFβ1 resulted in a time- and dose-dependent inhibition of ³H-thymidine incorporation into cells. Melatonin (10-500 pM) inhibited ³H-thymidine incorporation, and its effects were attenuated at higher (1-10 nM) concentrations. In the presence of submaximal doses of TGFβ1, the inhibitory effect of melatonin was maintained over the entire concentration range tested (10 pM-10 nM). The inhibition of ³H-thymidine incorporation by TGFβ1 was more pronounced in the absence of dihydrotestosterone (DHT) than in its presence, and melatonin had no further effect. Melatonin enhanced the release of proteins from cells, among them proteins recognized by specific TGFβ1 antisera. The TGFβ1- neutralizing antisera prevented the inhibitory action of melatonin on ³H- thymidine incorporation into cells. CONCLUSIONS. These data indicate a role for TGF 1/4 in the melatonin-mediated attenuation of benign prostate epithelial cell growth.